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Adrienne Reitz, Clopay Corporation's Director of Marketing Communications, defines R-value, U-value, and U-factor and reveals how these numbers can be interpreted to determine the thermal efficiency of your sectional or rolling door.
The difference between R-value, U-value, and U-factor is something we get asked about a lot.
What is R-value?
Typically, you see R-value listed for building materials. And for most building materials, like drywall, that’s fine, because since it’s solid, and there’s not separate components. So taking a measurement here, here, or here on a wall, you’ll get the same thermal performance. And for R-value, higher is better.
Rolling or sectional doors are a different story. R-value, which is calculated, can only determine the resistance of heat transfer of a given component, usually the slat or the section. It doesn’t take into account the entire door assembly – the guides, the perimeter seals, and things like that.
What is U-factor?
U-factor, on the other hand, is a third-party tested rating that takes the entire door assembly into consideration, making it a much more accurate measure of thermal efficiency. We like to think that U-factor is factual – since it’s tested. For U-factor, lower is better.
What is U-value?
And P.S. – U-value is NOT the same as U-factor! We see this a lot. U-value is an inverse of R-value and it’s commonly mistaken for U-factor in the industry.
